Differential expression of estrogen receptor α and β immunoreactivity in the human supraoptic nucleus in relation to sex and aging

Abstract

The dorsolateral supraoptic nucleus (dl-SON) is the main production site of plasma arginine vasopressin (AVP). Plasma AVP levels and the activity of AVP neurons in humans are higher in males than in premenopausal females. On the other hand, an increased activity of AVP neurons becomes prominent in postmenopausal women who have strongly decreased estrogen levels. As estrogens are presumed to inhibit AVP production in a receptor-mediated way, we studied estrogen receptor (ER) α and β immunoreactivity in the dl-SON. Hypothalami of 34 controls were subdivided into 4 groups within a 50-yr boundary (young men, young women, elderly men, and elderly women). The AVP part of the dl-SON of young women contained 50 times more neurons with ERβ nuclear staining than that in young men and 250 times more than that in elderly women. In addition, young women also showed more ERβ cytoplasmic staining than young men and elderly women. In contrast to the ERβ immunoreactivity, no differences were found in the number of ERα-positive neurons in the 4 groups, but the age and sex pattern of ERα staining was basically opposite that of ERβ. Significant correlations between the percentage of ERβ- and ERα-positive and -negative AVP neurons and age were found in women, but not in men. Our data demonstrate for the first time a strong decrease of ERβ and an increase of ERα immunoreactivity in AVP neurons of the dI-SON ofpostmenopausal women. Both receptor changes are proposed to participate in the activation of the AVP neurons in postmenopausal women.